Highlighter is basically an annotation/highlighting tool, allowing the user to annotate in different colors, nearly everywhere.
The app is pretty useful for me, because I do a lot of researching on the internet with my device, allowing me to annotate everything important I read and save it in the gallery, just by doing a simple screenshot.

As soon as HighLighter is active, it draws a little "always on top" button in the upper left corner of your screen, toggling the "annotation" feature on and off when pressed!.
But the special thing is, that HighLighter allowes the user to annotate OVER the "windows" of apps, running besides highlighter, giving the user the ability, to annotate even SMS, the homescreen, pictures in the gallery . . ., for example.

All in all, I was pretty impressed, how helpful, such a small annotation tool can be !.